A membrane switch is an electrical switch for turning a circuit on
and off. It differs from a mechanical switch. Membrane switch is
very thin and soft. The touch surface material usually is PET or
PC. The circuit can be PET, FPC or even PCB. Membrane switches are
user-equipment interface utilities that allow for the communication
of commands from users to electronic devices.

> Construction:

A membrane switch typically has 6 or more or less layers. The top
layer of a membrane switch is the graphic overlay interface between
the user and the machine. The other critical layer is a the circuit
layer. It can also be PET, FPC or PCB. All the layers are normally
assembled using pressure-sensitive adhesives. Contact between two
traces can be made through a printed shorting pad or through a
metal dome that stands on legs.

And also there are many other kinds of structures for the interface
keypads structure. It based on customer’s real needs and we can
design the suitable and economical structure for our customer’s
final application.